More than 230 small earthquakes have hit parts of Alaska since Friday, when a 7.0-magnitude quake knocked out power, ripped open roads and splintered buildings near Anchorage, the US Geological Survey said.

Most of those smaller earthquakes were not strong enough to be felt, but a magnitude-5.2 aftershock about 11 p.m. Friday was the second-biggest event since a magnitude-5.7 temblor hit minutes after the main quake, according to Gavin Hayes, a research geophysicist with the USGS.

"That would have given people a shake and probably a bit of a scare given what they went through yesterday," he told CNN on Saturday.

The magnitude-7.0 earthquake sent residents scurrying for cover when it hit about 8:30 a.m. Friday local time. The quake was centered 10 miles northeast of Anchorage, the state's largest city.

"The most striking thing about this event was that it was so close to Anchorage," Hayes said. "That's why it has caused the damage that we're seeing. Had it been a little further away from Anchorage I don't think it would be getting very much attention. It's not an unusual earthquake in the perspective of the tectonics of the region."

'This was a big one'

"It was very loud when it came," Anchorage Mayor Ethan Berkowitz said. "It was very clear that this was something bigger than what we normally experience. We live in earthquake country ... but this was a big one."

Roads buckled under passing cars and grocery store products tumbled from shelves. In court, panicked attorneys scurried under tables as a room rocked from side to side.

Despite the chaos and confusion, Anchorage authorities said Friday night that no fatalities or serious injuries were reported. Authorities didn't have firm figures on damage Friday night. Helicopters and drones were assessing infrastructure across the region.

Seismologists predict more aftershocks

Philip Peterson was in a multistory building in downtown Anchorage as the structure swayed and coffee mugs fell from tables and tiles from the ceiling.

"I just jumped under my desk and had to ride it out," Peterson said.

The 7.0 earthquake was felt up to 400 miles outside of Anchorage, said Michael West, the Alaska state seismologist.

He called it the most significant earthquake in Anchorage since 1964.

"I think it's safe to say that, not measured in magnitude or location but in terms of how strong the ground itself shook during the earthquake," he said during a question-and-answer session at the University of Alaska, Fairbanks.

Two of the city's main hospitals -- Alaska Regional and Providence Alaska Medical Center -- sustained damage but emergency rooms were open, according to hospital officials.